#对象、类及从属关系
##Animal is-a object (yes,sort of confusing) look at the extra credit
class Animal(object):
   pass

##??
class Dog(Animal):

   def __init__(self,name):
       ##??
       self.name=name

##??
class Cat(Animal):

   def __init__(self,name):
       ##??
       self.name=name

##??
class Person(object):

   def __init__(self,name):
       ##??
       self.name=name

       ##Person has-a pet of some kind
       self.pet=None

##??
class Employee(Person):

   def __init__(self,name,salary):
       # ?? hmm what is this straange magic?
       super(Employee,self).__init__(name)
       ##??
       self.salary=salary

##??
class Fish(object):
    pass

##??
class Salmon(Fish):
    pass

##??
class Halibut(Fish):
    pass


## rover is-a Dog
rover=Dog("Rover")

##??
satan=Cat("Satan")

##??
mary=Person("Mary")

##??
mary.pet=satan

##??
frank=Employee("Frank",120000)

##??
frank.pet=rover

##??
flipper=Fish()

##??
crouse=Salmon()

##??
harry=Halibut()
